Re: GPL only modules [was Re: [GIT PATCH] more Driver core patchesfor 2.6.19]

[Alan]

On Wed, 13 Dec 2006 22:01:15 -0800
"Hua Zhong" <hzhong@xxxxxxxxx> wrote:

> > I think allowing binary hardware drivers in userspace hurts 
> > our ability to leverage companies to release hardware specs. 
> 
> If filesystems can be in user space, why can't drivers be in user space? On what *technical* ground?

The FUSE file system interface provides a clean disciplined interface
which allows an fs to live in user space. The uio layer (if its ever
fixed and cleaned up) provides some basic hooks that allow a user space
program to arbitarily control hardware and make a nasty undebuggable mess.

uio also doesn't handle hotplug, pci and other "small" matters.

Now if you wanted to make uio useful at minimum you would need

-  PCI support
-  The ability to mark sets of I/O addresses for the card as
"unmappable", "read only", "read-write", "any read/root write", "root
read/write"
-  A proper IRQ handler
-  A DMA interface
-  The ability to describe sharing rules

Which actually is a description of the core of the DRM layer.
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